The invention relates to a spot-type disc brake for automotive vehicles with a floating caliper displaceably borne on a brake support fixed to the vehicle, the caliper embracing a brake disc as well as brake pads arranged on both sides of the brake disc and the brake pads being axially displaceably guided in the brake support.
A spot-type disc brake of this kind is known e.g. from U.S. Pat. No. 5,984,163. Here the brake pads are axially displaceably guided on a brake support and, at the same time, radially secured on the support. Further on, the brake pads are radially rigged with respect to the brake support by means of spring sheets in order to hold the brake pads constantly in contact with the brake support. The brake caliper, being a floating caliper, is axially displaceably borne on the brake support. In particular with high brake caliper weights, such an arrangement tends to undesired rattling noises which are caused by judder, particularly during driving on bad-road stretches. Here the suspension of the brake pads or the brake caliper, respectively, versus the brake support turns out to be insufficient. Furthermore, the spot-type disc brake is hard to assemble, for the brake pads and the brake caliper can only be fixed to the brake support in several individual working steps.
From DE 4 318 744 C1, also a floating caliper disc brake is known which provides a brake carrier integrated into the steering knuckle of the vehicle for supporting the peripheral forces and for guiding the brake pads. In order to simplify the final assembly, the floating caliper with brake pads fixed to it is delivered as a pre-assembled unit. The brake pads are each releasably fixed to the brake caliper by means of leaf springs. The leaf spring of thexe2x80x94with respect to the vehiclexe2x80x94outer brake pad additionally serves to radially bias the brake caliper relative to the brake carrier. By this means, the floating caliper is supposed to be radially supported relative to the brake carrier via the leaf spring fixed to the outer brake pad. In particular with heavier floating caliper embodiments and during strong judder, however, the floating caliper is set into oscillation that cannot be compensated by the leaf spring. The arrangement thus tends to generating undesired rattling noises.
Based on this, the objective of the invention consists in improving the guidance of the brake pads as well as of the floating caliper on a vehicle-fixed brake support for a generic spot-type disc brake in a way that undesired rattling noises are avoided and, at the same time, an easy-motion floating caliper guidance is attained.
This objective is achieved by means of the features of patent claim 1. Accordingly, the spot-type disc brake for automotive vehicles comprises a floating caliper displaceably guided on a vehicle-fixed brake support, which caliper embraces a brake disc as well as brake pads arranged on both sides of the brake disc. The brake pads are also axially displaceably guided in the brake support as one brake pad is radially fixed in the brake support and the floating caliper is radially supported on this brake pad. Here, the floating caliper is preferably radially locked on the brake support, maintaining a limited play via the brake pad. Thus, the degree of freedom of the brake pads and the brake caliper, respectively, is strongly limited in radial direction, which greatly reduces the proneness of the entire spot-type disc brake to rattling.
An advantageous refinement of the spot-type disc brake is achieved in that the floating caliper has a first housing leg with at least one actuation unit on one side and a second housing leg with an adjacent brake pad on the other side of the brake disc. The two housing legs are connected to each other via a bridge section spanning the brake disc, where the second housing leg is radially supported on the brake support via the brake pad. The second housing leg isxe2x80x94with respect to the vehiclexe2x80x94usually located on the outside while the first housing leg with the actuation unit is arranged on the inside. This means that on the inside, i.e. on the first housing leg, the floating caliper is directly borne on the brake support, in particular by means of a pin guide, and on the outside, i.e. on the second housing leg, it is radially fixed to the brake support via the brake pad there.
A preferred embodiment of the spot-type disc brake results from the fact that an inner brake pad connected to the actuation unit is radially removably supported in the brake support. Thus, the two brake pads are designed differently. While the inner brake pad is radially removably arranged in the brake support, the outer brake pad is radially locked in the brake support. Nevertheless, both brake pads are axially displaceably guided in the brake support. By way of the different design of the brake pads, particularly the inner brake pad can be easily mounted radially, preferably together with the brake caliper.
In order to improve the gliding or guiding properties, respectively, between the brake pad and the brake support, it is provided that between each of the brake pads and the brake support at least one gliding element is placed that prevents a direct contact between brake pad and brake support. Such a gliding element can be specifically designed so that the brake pads are freely displaceable along the gliding element for any state of operation of the brake.
The gliding element, in particular, is designed in a way that it radially rigs the brake pad, which is radially fixed to the brake support, with the latter. In this regard, an additional spring for rigging the brake pad on the brake support can be dropped because the brake pad is already fixed without rattling onto the brake support by means of the gliding element. Advantageously, the gliding element is designed as a one-piece sheet metal element, for as a sheet metal element, regarding a favorable manufacturablility, it can easily and flexibly be adapted to the respective design demands.
An advantageous embodiment of the radial fixation of the floating caliper to the outer brake pad results from the fact that the floating caliper is radially fixed to the outer brake pad by means of at least one locking pin located on the second housing leg. The locking pin extends axially in a passage opening of the second, outer, housing leg and, at the same time, protrudes with little play into a bore of the outer brake pad. By this means, the floating caliper is fixed with respect to the outer brake pad, where the outer brake pad itself is radially fixed to the brake support.
A further variant of the spot-type disc brake is attained in that the brake pad arranged on the second housing leg, i.e. on the outside, is axially rigged on the second housing leg by means of a spring element. Thus, the outer brake pad is continuously kept in contact with the second housing leg. An additional simplification results from radially supporting the second housing leg directly on the spring element, where the spring element itself is fixed to the brake pad. An additional locking pin can be eliminated for such a case. The spring element can particularly easily be radially snapped into a groove-like recess on the second housing leg. Alternatively, the spring element can be radially anchored in an associated bore on the second housing leg. A double function is assigned to both embodiments of the spring element. On the one hand, the outer brake pad is axially kept in abutment on the outer housing leg and, on the other hand, the radial lock of the brake pad on the outer housing leg is warranted.